SiteIt's Saturday, 11pm. The wrapper on line 2 has stopped, and the shift manager rings the on-call number. It rings out. They try again. Then they try the fitter who was on call last week, who's had a drink and can't drive in.
By the time someone answers, it's gone midnight. The engineer who comes in lives 40 minutes away and was up at six for a day shift.
The rota on the office wall had a name for every weekend. On paper, the site was covered.
Most on-call rotas fail like this. Quietly, at night, when the plant needs them most. The rota exists, but people don't want to do it, so they swap, dodge or let the phone ring.
Why engineers hate on-call
Ask your team and you'll hear the same things. The pay doesn't match the disruption. A week on call means a week of staying close, staying sober and sleeping with the phone by the bed. The calls come at the worst times. And the same two people end up doing most of it, because they're the ones who pick up.
The tiredness is real. HSE's guide to shift work says people on standby or on call "have not entirely finished work". Called out or not, they may get poor sleep and build up fatigue (HSG256). The same guide lists workers who stay on call through the night or weekend after a normal day's work as a group to think about in your risk assessment.
So a rota that leans on a few willing people wears them down. Then they leave, and the rota gets thinner.
What counts as working time
Get the rules straight before you touch the pay.
GOV.UK counts time on call at the workplace as part of the working week. Time on call away from the workplace doesn't count towards the 48-hour average* (GOV.UK, calculating working hours). HSE's guide agrees: if the worker must be on site, the time counts as working time, whether they're working or not.
Once they're called in, the hours on site are work, and daily rest starts to matter. Workers have the right to 11 hours* rest between working days (GOV.UK, rest breaks). Shift workers who can't get it may be entitled to compensatory rest instead (GOV.UK, compensatory rest). So an engineer called in at 1am and due back on days at 7am has a problem. So do you.
HSE's fatigue guidance goes further. Following the Working Time Regulations alone "is insufficient to manage the risks of fatigue". The duty sits with you, whatever the engineer's "willingness to work extra hours" (HSE, fatigue). An engineer who says "I'm fine, I'll do days as well" doesn't take that off you.
The drive in is part of the job
The risk starts in the car, well before the machine. HSE's tips for shift workers say driving to and from work can be risky after a long shift, a night shift or before an early start (HSE, hints for shift workers).
Then there's the site. Your on-call engineer often walks into a quiet plant with one shift manager and a few operators. HSE's lone working guide names maintenance and repair staff who work outside normal hours. Some high-risk jobs may need at least one other person there, such as work near exposed live conductors (INDG73). Plan for that before the 2am call. Our post on lone working on nights covers what a good system looks like.
A rota people will stick to
Here's what we'd build.
- Enough names. In our view, one week in four is about as much as most people will live with. One week in two turns on-call into a second job.
- Pay for the week, then pay for the call. A standby payment for being tied to the phone, and a call-out rate with a minimum number of hours once they come in. Set it so people would rather be on the rota than off it.
- A response time in writing that matches where people live. If the engineer is 40 minutes away, a 30-minute response is fiction.
- The rest given back. If the call runs past midnight, the next shift starts late. Write that rule down so nobody has to ask for it.
- Swaps through one person, and recorded. HSG256 says supervisors should monitor and record shift swaps, and check rest periods before agreeing one.
- A second line. A named back-up, plus a clear point where the shift calls outside help. Our 30-minute rule sets that point.
Make the first ten minutes count too. A good on-call engineer can often fix it by phone: talk an operator through a tripped overload, read the alarm off a photo of the HMI, or tell them to leave it for days. Give them the photos and the drawings on their phone, and you'll save a lot of drives in.
Skill gaps break the rota
The rota also fails when the person on call can't fix what's broken. A mechanical fitter on call for a drive fault will drive in, look, and ring the one controls engineer anyway. Now two people are up instead of one, and the line still waits.
Check the rota against your skills. If one person covers every PLC fault, they're on call every week, whatever the wall chart says. Our post on single-skill risk shows how to spot it.
Then put a price on the gap. Work out what two extra hours of a stopped line cost on a weekend night. Our guide to the true cost of downtime walks through the sums. Set that against a year of standby pay. Most sites find the rota is the cheap part.
Our view
A rota only works if it's the easy choice for the engineer. Pay it properly, give the rest back, and never let it rest on two names. When you can't fill it, cover the gaps from outside rather than stretching the same people again. HSE says problems with overtime and shift-swapping "may indicate inadequate resource allocation and staffing levels". We'd say the same about an on-call rota nobody wants. If the same faces keep covering nights, have a look at how your night cover is set up as well.
What to do on Monday
- Count who actually answered the on-call phone in the last three months. Compare it with the names on the rota.
- Check every call-out against the 11-hour* rest rule for the next shift.
- Write down the back-up name and the point where the shift calls outside help.
- Ask your team what on-call pay would make them want a slot.
* The 48-hour average, the 11-hour daily rest rule and what counts as working time correct as of 21 September 2026. Check GOV.UK on calculating working hours and GOV.UK on rest breaks for the latest.